This invention relates generally to rotary machines, and more specifically to airfoils used with rotary machines.
At least some known rotary machines such as, but not limited to, aircraft engines, gas turbine engines, and steam turbine engines, include a plurality of rotating airfoils which channel an airflow downstream. As a result, a wake flow may be generated and channeled downstream where it may impinge against an object downstream from the airfoils. Depending on the object, wake flow impingement may generate noise and/or aeromechanical loading. In some known engines, noise may be generated by either the upstream rotating airfoil wake impinging on a stator or rotor component downstream from the rotating airfoil, or the upstream stator component wake impinging on a rotating airfoil downstream from the stator component. Moreover, in some known engines, the wake flow may contain non-uniform temperature distributions.
The generation of such wake flow may result in a loss of engine performance and engine efficiency. Reduction of the amplitude of the wake flow may reduce the noise and the aeromechanical loading generated when the wake impinges against a downstream object. At least some known methods of reducing the amplitude of the wake flow and/or providing thermal uniformity of the wake flow include increasing the distance between the upstream airfoil and the downstream object. This increased distance mixes the wake flow and thus reduces the amplitude of the wake flow.
Increasing the distance between upstream airfoil and the downstream object increases the size, weight, and cost of the engine, and thereby reduces the efficiency and performance of the engine.